Exam 2 Flashcards
Interphase
Nucleus is visible and cell function occur
G1, S, G2
G1
btw cytokinesis and S phase
Chr are single
new organelles are formed
cell grows in size
Restriction point
G1-S transition
commitment to DNA replication and division
Can put cell in G0
G0
Resting phase. Quiescent or Senescent
Quiescent
Reversible. lack of cell growth signals
growth inhibitory signals (TGFBeta)
DNA dmg detected by p53
Senescent
Irreversible. telemoere shortening
still can function. alt to apop
S phase
DNA replicates
Sister chromatid remain together
G2
Prepares for mitosis
M phase
Mitosis
Prophase, metaphase, anaphase, telophase
G1/S
DNA damage checkpoint: S phase blocked
G2/M
checks if replication is complete
SAC
Anaphase blocked if chromatds are not properly assembled on mitotic spindle
CDKs
Cyclin dependent protiens
Ser/Thr
activated by binding to cyclin
CK4/6
Cyclin D - G1 pase
CDK2
Cyclin E - G1/S
Cyclin A - S
CDK1
Cyclin A - S/G2
Cyclin B - M
Inhibitors for CDK-Cyclin Activity
D-CDK4/6 = p16,p15,p18,p19
Cyclin E,A,B = p21,p27,p21
TGF beta
Induces p15 and p21
p53
inhibits through p21
pRb
inhibits cell cycle at R pt - binds to E2F
extensive phosphorylation of RB allows cell cycle progression
Cyclin D-CDK and Cyclin E-CDK control phosphorylation
Mitosis promoting Factor (MPF)
G2-M transition
Cyclin B combines with CDK1 = MPF
reaches critical lvl at end of G2 and counts to peak through M
Activates Anaphase promoting complex (AC/C)
SAC
Spindle assemble checkpoint
INhibits APC/C until CHR aligned on metaphase plate and checks kinetochores
4 modes of cell singaling
Endocrine = insulin
Paracrine = GF
Synpatic = AcH
Contact Dependent = Notch
Growth Factors
molecules released by cell that signal other cells
promote differentiation and maturation
Cytokines
proteins involved in immune response
Hormones
proteins, steriods, fatty acid derivatives produced by endocrine glands (long range)
Enzyme - coupled receptors
act as enzymes/ assosiate with enzymes in the cell
Control cell growth, proliferation, differentiation, survival
Ligands
Receptor - Tyrosine kinases (RTKs)
enzyme coupled
3 domains = Extracellular, Transmembrane, Cytoplasmic
Activates Ras, PI-3K
Dimer
2 receptor molecules associate
PI-3K signlaing
promotes cell survival
PI-3K works
1) PI3K binds to RTK and phosphorylates
2) PI-33k Phosporylates PIP2 which makes PIP3
3) PIPs recruit Akt and PDK1
4) PDK1 and mTor phosphorylate Akt
5) Akt released into cytosol where activates other intracellular proteins
6) Akt activates Bad, pro-apoptotic protein
7) Bcl2 released and promotes cell survival
PTEN
dephosphorylates PIP3
Tumor Supressor
men with prostate cancer have lost this
Mechanisms for targeting growth factor receptors
Downstream pathways
anti-ligand
Anti receptor
Receptor inhibitor
Anti ligand
use antibodies to target ligand
Anti receptor
use antibodies target the RTK
Receptor inhibitor
molecule inhibitor of RTK to reduce activity
HER2
gene encoding for RTK
overexpressed in breast cancer
Herceptin (traztuzibmab)
HER2 therapy
blocks downstam HER2
Flags HER2+ cells for destruction
Signal diversity
receptors activate multiple intracellular pathways
multiple effects of one signal receptor
Cross talk
pathways regulated by other pathways
Redundancy
pathways activated by more than one receptor
Diff signals but similar effects
Signal amplification
multiple steps in pathway allows for signal to be amplified
small amt of ligand = big effects